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The Republican nominee invited Malik Obama, the president's half-brother, to sit in the audience at tonight's third and final 2016 presidential debate, at the University of Nevada in Las Vegas.

Malik Obama lives in Kenya but is an American citizen and reportedly supports Trump. Sources confirmed to ABC News that the Trump team paid for Obama's trip to the debate. No plans regarding Obama have been confirmed by Trump or his campaign.

At the last debate, in St. Louis, Trump took three women who have accused former President Bill Clinton of sexual misconduct. Trump also took a woman who in 1975 accused a man of rape; Hillary Clinton, who at the time ran a legal aid clinic at the University of Arkansas, was appointed by a court to defend the man. Trump held a press conference with the women — Juanita Broaddrick, Paula Jones, Kathleen Willey and Kathy Shelton — before the debate started, he mentioned them during the debate, and his campaign arranged for the women to speak to the press in the spin room afterward.

White House press secretary Josh Earnest said he does not understand the intent behind the Trump campaign's invitation to Obama.

"I don't anticipate that the president has spent a lot of time considering whether or not [Obama] should attend the debate," Earnest said during today's White House press briefing. "I have to admit I really don't know exactly what the intent is of this invitation."

Trump has invited Leslie Millwee, a woman whose decades-old sexual assault allegations against Bill Clinton were made public for the first time today on the conservative news website Breitbart.

Mark Cuban, the owner of the Dallas Mavericks and a "Shark Tank" personality, is making his second appearance at a presidential debate this season. He was invited again by Hillary Clinton, who took him to her first debate with Trump.

Cant wait to give a big hug to my bestie @realDonaldTrump at the debate tomorrow night. I know you miss me !

Chelsea Clinton will be watching from inside the debate hall with her husband, Marc Mezvinsky, tonight, a representative confirmed to ABC News. She attended the two previous debates between her mother and Trump.

It was not clear whether Bill Clinton will be joining his daughter in the debate hall.

Unlike at the previous two debates — where the spouses of the candidates had to pass each other to get to their seats, shaking hands in the process — Bill Clinton and Melania Trump are not expected to shake hands with each other before the candidates are called to the stage.

Some of Hillary Clinton's other guests have personal connections to policy initiatives and issues that have come up in the campaign, including immigration and education programs for undocumented residents.

One such guest is 11-year-old Karla Ortiz, who lives in Nevada and has been featured in Clinton's campaign before. Most notably, she appeared onstage during the Democratic National Convention and is featured in one of Clinton's campaign ads. Karla was born in the United States but because her parents are undocumented, she reportedly fears that they will be deported.

ABC News' John Parkinson and John Santucci contributed to this report.